The present invention relates to a simulation system using computer graphics and a model expression method in the simulation system.
Recently, simulation systems using computer graphics are being developed as educational training systems for various instrumental operations.
Such simulation systems have been first developed as control training systems for airplanes and are, at present, gradually finding use as new medical simulators in the field of medical treatment.
In the field of medical treatment, the use of a simulation system of this sort as a support system for laparoscopic surgery is being examined on the research level.
Laparoscopic surgery is a surgical technique by which insertion holes as small as about 10 mm in diameter are formed in several portions of a patient's body and a laparoscope and forceps are inserted through these insertion holes to perform all processes such as incision, extraction, and suture, similar to those performed in abdominal operations, while monitoring images through the laparoscope.
This surgical technique is not only less invasive but also less dangerous in terms of the possibility of complications after surgeries than conventional surgical techniques which scalpel a wide area of a patient's body. Accordingly, this surgical technique is being greatly expected with the recent increasing medical expenses and increasing population of advanced age in the background.
In these medical applications, making the operation or deformation of an organ model as an object in a simulation system look like the motion of an actual organ is particularly a big technical problem.
Conventionally, organ models on these simulation systems are expressed by pasting polygonal geometric planes called polygons; all polygons continue to each other to express one structural body.
In dividing a structural body such as when a new end portion is to be formed by incision, therefore, a portion which can be incised is previously determined, and polygons in that portion are not connected from the beginning. That is, these polygons are moved away from each other as an operating means which defines an incising action approaches. Alternatively, at the start of an incising action, whole model data is rewritten for an entirely new organ model, thereby drawing the new organ model.
Since, however, a conventional organ model is expressed by pasting polygons, a given portion cannot be divided by incision in the former method in which the portion that can be incised is previously determined. In the latter method of rewriting whole model data, on the other hand, an organ model is difficult to draw in real time because an enormous amount of calculations must be performed.
As described above, organ models expressed by using polygons on conventional simulation systems have already reached their limits in reproducing the reality of motion of an actual organ.